A galvanometer acting as a voltmeter will have
Show Hint
Galvanometer detects small electric current flowing in the circuit and a Voltmeter measures the potential drop across the two ends of a circuit element.
- a high resistance in parallel with its coil
- a high resistance in series with its coil
- a low resistance in parallel with its coil
- a low resistance in series with its coil
The Correct Option is B
Solution and Explanation
A galvanometer acting as a voltmeter will have a high resistance in series with its coil.
A galvanometer requires a very small current to cause notable deflection in the dial. Thus, it is a very sensitive instrument. A galvanometer can be converted to a voltmeter by making the resistance higher. This can be done by adding it in parallel between the points across which we intend to measure the voltage drop. This makes the galvanometer exposed to the same voltage value that is being measured.
A voltmeter is thus a modified form of a pivoted coil galvanometer. To prevent damage to the instrument, only a small current needs to be passed through it which is achieved by putting a high resistance in series with the galvanometer coil. The resistance value is dependent on the working range of the voltmeter.
Also Read: Current Electricity
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Concepts Used:
Electrical Instruments
There are various electrical instruments used to measure current, power, voltage, etc. Some of them are briefly explained below:
Moving Coil Galvanometer
- It is an electromagnetic device which measures small values of current.
- Its working principle is that whenever a current loop is placed in a magnetic field, it experiences a certain torque. The value of that torque can be modified by modifying the current in the loop.
- For a current carrying loop having N turns, and cross sectional area A, carrying current i, whenever it is placed in and along the direction of an external magnetic field B, it experiences a torque given by:
ԏ = NiAB
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